Data collected from 34 countries (out of 41 and Bucharest) representing 76.17% population of the country (i.e. 17, 232, 817 inhabitants) involve 4424 definite MS cases (2397 females and 2027 males with a F/M ratio 1.18:1). On the prevalence day (July 1, 1984, the mean prevalence) rate was established at 25.7% population and a mean incidence rate 1.78 % (1980-1984). By adding the results from other previous two studies, including the capital Bucharest (898 MS cases) and a county (162 MS cases) (prevalence day January 1, 1977) we could modify the prevalence rate up to 30%.